In the scope of the production or processing of workpieces of the same type, it is often required to perform several processing steps on such a workpiece one after the other. For this purpose it is known to transport the workpiece to different processing stations of a production machine by means of a workpiece carrier circulating system. Such a workpiece carrier circulating system comprises only two essential elements, namely, for one, the workpiece carrier itself that has a workpiece receiver that is designed with respect to the workpiece to be held. During several work processes, the workpiece remains on this workpiece carrier or in the workpiece receiver and the workpiece carrier is moved from one processing position to another. For this purpose, on the machine side there is a corresponding holder as the second part in which the workpiece carrier is detachably inserted or on which it is held detachably for the period during which it is located in the processing area of the production machine. Such workpiece carrier circulating systems can be used, for example, in carousel machines or rotary table machines that are often used in the automotive industry, or in installation, testing, and labeling machines, as well as in feeding systems for machine tools. The use of such workpiece carrier circulating systems is also conceivable in labeling machines of container processing and bottling systems for adhering labels onto containers and bottles that here form the workpieces. Each conveyor operation can be continuous or cycled, wherein, depending on the conveyor operation, each process takes place in a processing station either on the workpiece currently moving by in continuous conveyance or during the holding operation. The corresponding work can be of a wide range of different types. It could be either installation processes, that is, additional individual parts are attached to the held workpiece. It could be testing or measurement processes. It could be printing or labeling processes, for example, by means of pad printing or inkjet printing, etc.
The essential elements are, as described, the workpiece carrier and the holder that temporarily and detachably holds it. In this way, the workpiece carrier is typically held tightly in the holder. Consequently, it is required, however, to move the workpiece into a certain position, for example, bottles to be labeled must be rotated about their longitudinal axis, to enable labeling. For this purpose, it is known to rotate the bottles themselves by means of a corresponding rotary drive, wherein these bottles are held accordingly so that they can move in the workpiece holder. Alternatively, it is known to couple the workpiece carrier detachably and temporarily to a drive as such at the processing station, where workpiece rotation is required, in order to rotate it after detachment from the holder. All of these constructions for enabling workpiece rotation are very complicated and they require special drives or mechanical couplings and are also susceptible to disruptions.